sorry it took so long to respond, but the Headers are Hedman but I do not have a part number. They do clear the frame but not by much, can barely get my fingers between the frame rails and headers but they do not even rub under the twisting of the motor

The motor is sitting on stock big block mounts in the stock location

hope this helps guys anything else just let me know, the motor is coming out in a couple weeks!!!!

whats the best way to mount a bb in, I was going to order the DI4Yx crossmemeber or should I just look for a set of bb mounts for the sbc crossmember or replace the whole crossmember and where would I get those parts?

I used the DIY crossmember and it did not fit well...when I bolted it to the frame, it pulled the frame rails in...moving the engine mounts in by a 1/4"...I actually had to get the hot-wrench out and heat up the center of the crossmember, then use a porta-power to "spread" the frame rails back out to where they should be...stretching the crossmember at the same time.
I also installed a 2" body lift. I had to "clearance" the firewall for the HEI and tall valvecovers...as it is, I have about a 1/4" of clearance between the valvecovers and the firewall...I figure they will "self-clearance" when I get on the 468. I had to notch the frame a lot to clear the Corvette manifolds...so much so on the pass side, that I had to box it in with 1/4" plate to stiifen that part of the frame..(really wanted run those manifolds, lol).
Note: I did not move the drivetrain forward. I should have. Would have given more clearance all the way around.
Here are some pics

I have the factory crossmember and there is no way I would have cleared the valve covers with the firewall without some "massagin" (beating with a hammer. I hate the idea also but it is not noticabel once the motor is installed. Not that that makes it an easy choice!!!

I did notch the frame rails so the headers had more clearance. The headers now slide in nicely from the top or bottom.

Belwo are some pics, in one of them you can see the notched frame. As you can tell from the pics BBC are a tight fit at the firewall. If I was to do it all over and had the time to mock everytihng up a couple times I would slide the motor forward about 1 1/2''. I would still have plenty of room between my pulleys and electric fans!

Hi did my 71 gm k2500 20 + yrs ago, motor came from a 68 chevelle.
used this oil pan and put on the sb mounts. used a set of chevelle headers that cleared the frame rail, then switched to 68 camaro exhaust manifolds that easily clear the frame. Had to dent the firewall in about 1/2 for hei clearance as it was rubbing the firewall. I would suggest the electronic conversion kit from pertronics that uses a point distributer and converts it to electronic, that solves the clearance problem.Forgot to add that I also used the corvette valve covers

I did one in my 1972 c10 4x4. I used the small block motor mounts the factory 1966 396 impalla valve covers with one of the sloped corners and a hei distributor. A short water pump and I had to hunt for a factory pan that would clear the cross member. The headmen headers for a 2 wheel drive fit except the pass side hangs too low to clear the front drive shaft. So I used factory manifolds. I cut the small block fan shroud down and it still works. With mine you can not use aftermarket valve covers. The only hacking I had to do was to trim the front cross member under the radiator a sliver abot a 1/2'' or so to clear the harmonic ballancer pulley that was it. My truck has factory air and I didnt have to mess with the heater box either. When I swapped in the 396 I also swapped to a 4 speed/np205 from a th350/np205. I hope this helps ya .

They look like the correct stamped steel "style" of cover but maybe a bit taller.... I'm trying to find a retro-looking set for my 502, but I am hearing that the stock BBC covers won't clear the rockers. I suppose I could use a set of valvecover spacers as a last resort.